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Full text of "The manufacture and properties of iron and steel"

CHAPTEE  VI.
THE ACID BESSEMER PEOCESS.
SECTION Via.—Construction of a converter.—The acid Bessemer process consists in blowing air into liquid pig-iron for the purpose of burning most of the silicon, manganese and. carbon of the metal, the operation being conducted in an acid-lined vessel, and in such a manner that the product is entirely fluid.
The way the air is introduced is of little importance. In the earlier days there were many forms of apparatus, the air being blown sometimes from the side and sometimes from the top, while the tuyeres were plunged beneath the surface or raised above it. These forms have given way in large plants to the method of blowing the air upward through the metal, trusting to the pressure of the blast to keep the liquid from running into the holes in the bottom, but where converters are used for making steel castings the method of side blowing is employed, for with intermittent work and where there is difficulty in getting the metal hot, the blast over the surface is an advantage. The converters vary in size, in exceptional cases holding less than one thousand pounds, but the common size for what are known as "small" plants treats five tons at a time, while in the "large" plants the capacity is from ten to twenty tons.
In Fig. VI-A are given drawings of the 18-ton vessels in use at the works of the Maryland Steel Company, at Sparrow's Point, Md. The converters are rotated on a central axis by means of a rack and pinion, to allow the turning down of the vessel as soon as the charge is decarburized, so that the metal may lie quietly in the belly, the tuyeres being above the metal. In this way the blast can be stopped without filling the .tuyeres with molten metal. If bottom blast be used with a stationary vessel, the blast must be continued during the time required tp open the tap-hole and drain out the metal, so that the results will be more irregular than with s,
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